This invention relates generally to shuttle valves and more particularly to a shuttle valve for use in a refrigeration system.
Shuttle valves of the type under consideration are known in the prior art. These valves are provided with pistons which close the entry ports and utilize a seal of such as an O-ring, or a synthetic sliding seal which crosses the ports. This arrangement has the disadvantage of damaging the piston seals by rubbing them against the margins of the entry ports. Alternatively, a precision metal-to-metal fit is used. With this arrangement also, the pistons are forced to slide across the entry ports to open and close the flow passages, with the disadvantage that high seat leakage is frequently experienced.
Another disadvantage of previous shuttle valves of this type is that a heavy spring is used between the pistons to urge them apart and ensure that both entry ports are never closed at the same time. The spring has to be sufficiently strong to overcome the pressure differential across the closed port. Unfortunately, using a heavily loaded spring between the pistons tends to cause misalignment of the pistons thereby aggravating the damage potential to the seals sliding across the entry ports. In addition, the use of a large spring between the pistons, because of the space taken up by the spring restricts flow through the inlet and outlet ports since flow to the common port is through the spring chamber.
The present shuttle valve solves these and other problems in a manner not revealed in the known prior art.